Scavenging Effects of Kaolin on Fine Ash Formation during Zhundong Coal Combustion

The previous work found that the additive kaolin could scavenge not only sodium(Na)but also calcium(Ca)and magnesium(Mg),which is the important ash fluxing agents in low rank coal combustion.Such scavenging effects of kaolin on fine ash formation were studied in the present work.A typical Zhundong coal and its blends with kaolin at dosages of 1,2 and 4 wt%were combusted in an electrically heated drop tube furnace(DTF)at 1300℃.The fine ashes generated were collected and size segregated by a low pressure impactor(LPI).The morphology and chemical composition of fine ash were analyzed by scanning electron microscopy equipped with an energydispersive spectrometer(SEM-EDS).In addition,char/ash particles were sampled at various positions of DTF to elucidate how kaolin additive affected the fine ash formation process.The results further showed that apart from the scavenging of volatile Na,kaolin additive could also strongly scavenge the refractory Ca,Mg and Fe in the fine ash during Zhundong coal combustion,which transformed the sintered particles with irregular shape into melted spherical particles,and finally resulted in the considerable decrease of these elements in both PM_(0.4)and PM_(0.4-10)by melting and agglomeration.The close contacts between kaolin particles and coal resulted from physically mixing were a key factor responsible for the reaction of kaolin with the refractory Ca,Mg and Fe.

Digital Geosciences and Quantitative Mineral Exploration

The idea of mineral exploration,which is called"exploration philosophy"in the Western countries,is the thoughts,the methodology,technology,goals and organization that guide mineral exploration.The three basic elements of mineral exploration are"what to find","where to find"and"how to find".The concept of mineral exploration is gradually changing with the development of these three elements that provide a powerful driving force to change mineral exploration concepts,methods and technology.Innovation of mineral exploration concepts is the result of continuing exploration and development keeping pace with the times.The combination of"mathematical geology"and"information technology"can be called"digital geology".Digital geology is the data analysis component of geological science.Geological data science is a science that uses the general methodology of data to study geology based on the characteristics of geological data and the needs of geological field work.Digital mineral exploration is the application of digital geology in mineral exploration to reduce ore-finding uncertainty.